| Titre | Compositional data analysis of hydrothermal alternations in IOCG systems, Great Bear magmatic zone, Canada: to each alteration types its own geochemical signature |
| Auteur | Montreuil, J -F; Corriveau, L; Grunsky, E C |
| Source | Geochemistry: Exploration, Environment, Analysis vol. 13, no. 4, 2013 p. 229-247, https://doi.org/10.1144/geochem2011-101 |
| Année | 2013 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20110237 |
| Éditeur | Geological Society Publishing House |a London (London) |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1144/geochem2011-101 |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 86E; 85N; 86C; 86D; 86E; 86F; 86K |
| Lat/Long OENS | -119.0000 -116.0000 66.5000 63.5000 |
| Sujets | minéralisation; oxydes de fer; cuivre; or; altération; altération hydrothermale; analyses géochimiques; interprétations géochimiques; Zone de Great Bear Magmatic ; géochimie; minéraux
métalliques |
| Illustrations | geochemical analyses; geochemical plots; location maps |
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| Programme | Gisements polymétalliques - Zone magmatique du Grand lac de l'Ours (T.N-O.), GEM : La géocartographie de l'énergie et des minéraux |
| Résumé | (disponible en anglais seulement)
Iron oxide copper-gold (IOCG) systems are characterized by a wide range of hydrothermal alteration types that indiscriminately and intensively replace their
host rocks over areas of >100 km2. At the scale of a system, element mobility and chemical changes associated with alteration are of a magnitude beyond that of any other types of hydrothermal systems and also affect normally immobile elements. Least
to non altered precursor rocks can be hard to find and in some cases the nature of the precursor rock itself remains uncertain as both original composition and textures have been severely modified. These properties of IOCG hydrothermal alteration
zones limit the applications of mass-balance systems analysis (e.g. Gresen's equations) for their lithogeochemical characterization. In contrast, principal component analysis (PCA) of whole-rock geochemical data from a large suite (386 samples) of
hydrothermally altered rocks has enabled the characterisation of the main signatures of the diagnostic alteration types as well as providing insights on coupling and decoupling of elements as alteration evolves. Samples were selected from the Port
Radium-Echo Bay and NICO-Sue Dianne IOCG districts and some IOCG systems of the central Great Bear magmatic zone (Fab and DeVries Lake) from the Northwest Territories in Canada. Results show that K-rich alteration is characterized by strong
enrichments in K, Al, Ba, Si, Rb, Zr, Ta, Nb, Th and to a lesser extent U. In contrast, calcic-iron alteration leads to strong enrichments in Ca, Fe, Mn, Mg, Zn Ni and Co. These variations in composition can be portrayed by a series of IOCG
alteration index and discriminant diagrams. Combined with an IOCG alteration sequencing model, documentation of the lithogeochemical footprint of IOCG systems provides a useful tool to identify areas favourable for IOCG mineralization, assess the
potential fertility and maturity of their host hydrothermal system and ultimately vector to ore during exploration. |
| GEOSCAN ID | 289399 |
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